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28. Implement strStr().go
28. Implement strStr()_test.go

28. Implement strStr()


Implement strStr().

Return the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

Example 1:

Input: haystack = "hello", needle = "ll"
Output: 2

Example 2:

Input: haystack = "aaaaa", needle = "bba"
Output: -1


What should we return when needle is an empty string? This is a great question to ask during an interview.

For the purpose of this problem, we will return 0 when needle is an empty string. This is consistent to C's strstr() and Java's indexOf().


实现一个查找 substring 的函数。如果在母串中找到了子串,返回子串在母串中出现的下标,如果没有找到,返回 -1,如果子串是空串,则返回 0 。



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